Well
crunchmeister's answer pretty much spells it, best to answer if you actually have used a CO2 with a WE Hi-capa or other CO2 guns (Though won't help much) if not then you might just be leading the questioner on a wild goose chase.
http://airsoftcanada.com/showpost.ph...7&postcount=25
http://airsoftcanada.com/showpost.ph...4&postcount=23
As for long term reliability you can only speculate